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* 3) The aligned portion contains enough space for the original number of
* elements requested.
*
* The macro then creates a pointer to the aligned portion of this array and
* assigns to the pointer the address of the first element in the aligned
* portion of the array.
*
* Calling the macro as:
*
* ALLOC_CACHE_ALIGN_BUFFER(uint32_t, buffer, 1024);
*
* Will result in something similar to saying:
*
* uint32_t buffer[1024];
*
* The following differences exist:
*
* 1) The resulting buffer is guaranteed to be aligned to the value of
* ARCH_DMA_MINALIGN.
*
* 2) The buffer variable created by the macro is a pointer to the specified
* type, and NOT an array of the specified type. This can be very important
* if you want the address of the buffer, which you probably do, to pass it
* to the DMA hardware. The value of &buffer is different in the two cases.
* In the macro case it will be the address of the pointer, not the address
* of the space reserved for the buffer. However, in the second case it
* would be the address of the buffer. So if you are replacing hard coded
* stack buffers with this macro you need to make sure you remove the & from
* the locations where you are taking the address of the buffer.
*
* Note that the size parameter is the number of array elements to allocate,
* not the number of bytes.
*
* This macro can not be used outside of function scope, or for the creation
* of a function scoped static buffer. It can not be used to create a cache
* line aligned global buffer.
*/
#define PAD_COUNT(s, pad) ((s - 1) / pad + 1)
#define PAD_SIZE(s, pad) (PAD_COUNT(s, pad) * pad)
#define ALLOC_ALIGN_BUFFER_PAD(type, name, size, align, pad) \
char __##name[ROUND(PAD_SIZE(size * sizeof(type), pad), align) \
+ (align - 1)]; \
\
type *name = (type *) ALIGN((uintptr_t)__##name, align)
#define ALLOC_ALIGN_BUFFER(type, name, size, align) \
ALLOC_ALIGN_BUFFER_PAD(type, name, size, align, 1)
#define ALLOC_CACHE_ALIGN_BUFFER_PAD(type, name, size, pad) \
ALLOC_ALIGN_BUFFER_PAD(type, name, size, ARCH_DMA_MINALIGN, pad)
#define ALLOC_CACHE_ALIGN_BUFFER(type, name, size) \
ALLOC_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
/*
* DEFINE_CACHE_ALIGN_BUFFER() is similar to ALLOC_CACHE_ALIGN_BUFFER, but it's
* purpose is to allow allocating aligned buffers outside of function scope.
* Usage of this macro shall be avoided or used with extreme care!
*/
#define DEFINE_ALIGN_BUFFER(type, name, size, align) \
static char __##name[roundup(size * sizeof(type), align)] \
__aligned(align); \
static type *name = (type *)__##name
#define DEFINE_CACHE_ALIGN_BUFFER(type, name, size) \
DEFINE_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
/* Pull in stuff for the build system */
#ifdef DO_DEPS_ONLY
# include <environment.h>
#endif
